Interpretive Summary: The dogwood borer has a broad range of deciduous hosts, including many species of woody ornamentals, nut trees and fruit trees. It is widespread in commercial apple orchards in eastern North America since the 1980’s. The larvae feed on the apple tree trunk which can lead to reduced growth and vigor of young trees and, in severe cases, tree death. A recently identified sex attractant enable us to address several fundamental questions about the mate-seeking behavior of male dogwood borer under field conditions, as well as emergence patterns of adult moths. Scientists and apple growers can use this information to develop behaviorally-based control strategies or improve management tactics for it is warranted.

Technical Abstract:
The emergence and pre-mating reproductive behaviors of adult dogwood borer moths, Synanthedon scitula Harris (Lepidoptera: Sesiidae) were examined under controlled conditions in the laboratory and in apple orchards in Virginia. The diel periodicity of male response to pheromone sources was recorded using traps baited with commercial pheromone lures and with a recently identified, trinary blend of dogwood borer sex pheromone components. An earlier study reporting a significant effect of pheromone trap height on the capture of male dogwood borer was revisited, using commercial lures and the new pheromone. Under a 16:8 L:D (h) photo regime, the emergence of male and female moths showed a diel periodicity, peaking at 0600 hours. Sexual receptivity of female moths, indicated by the onset of calling behavior, occurred in most individuals on the day following emergence and was observed only during the crepuscular period just before and after sunset. Similarly, the capture of male dogwood borer in traps deployed in July and baited with virgin female moths or pheromone lures, coincided with the period of female calling behavior, peaking sharply between 2000 and 2100 hours. When pheromone-baited traps were deployed in September, the peak capture of male dogwood borer occurred earlier, between 1900 and 2000 hours. Traps baited with a commercial lure captured significantly more male dogwood borer at 1.8 m (6 ft), while those baited the trinary dogwood borer sex pheromone captured similar numbers of males at elevations ranging from 1.2 to 2.4 m (4 to 8 ft).